Electronic enclosures may be used to house a variety of sensitive electronic components. An example electronic enclosure is a hard disk drive for a computer. Sensitive electronic equipment may be damaged or have its operation affected by the presence of moisture or various chemical species, such as hydrocarbons. Furthermore, the presence of particles, even of microscopic dimensions, can cause degraded performance or even catastrophic failure of electronic components.
An electronic enclosure is often required to have a breather vent to allow gas pressures on the inside of the enclosure to equalize with the atmospheric pressure outside the electronic enclosure. This is particularly important because the temperature of the electronic enclosure changes during operation, such that increased pressure is developed inside the enclosure and must be vented in a controlled fashion. Likewise, as the electronic enclosure cools, atmospheric air must be drawn in to prevent the pressure inside the electronic enclosure from dropping too low. Contaminants such as moisture, particles, or gaseous chemicals may enter an electronic enclosure in this way.
Contaminants can also be generated inside of an electronic enclosure. For example, various materials used to construct an electronic enclosure and its contained components may “off gas” harmful chemical species. Moreover, particles may be generated by the operation of an electronic component. For example, a disk drive that spins rapidly may generate particles as various components wear or in the event of contact between a moving part and a non-moving part.
Filters are typically placed in electronic enclosures to condition the gas inside the enclosure and to remove contaminants. Such a filter is typically placed over a breather opening in the electronic enclosure to allow the filter to filter air entering the electronic enclosure. The filter is also typically capable of filtering gases within the electronic enclosure. For example, in a disk drive, a rotating disk tends to set up rotating gas flow within the electronic enclosure. The filter can be positioned to interface with this gas flow, such that contaminants can be removed from the gas stream. A filter in an electronic enclosure may be capable of removing water vapor from the gas. A filter may also be capable of removing undesirable gaseous species, such as hydrocarbons, and particles.
However, traditional filters known in the art may actually be prone to generation of particles in some situations, thus resulting in the type of contamination that the filter is supposed to prevent. A typical filter composition includes silica gel to provide for absorption of water vapor inside the electronic enclosure. However, this silica gel can under certain circumstances escape from the filter, such as if the bonds or seals that contain the silica gel degrade or fail. Traditionally the size of those silica gel particles has been so small that they have not posed a risk in most circumstances. However, the lower tolerances of modern drives has resulted in the applicants identifying that even quite small silica gel particles can become a significant problem in electronic enclosures.
Notably, it is often difficult to prevent contamination of the exterior surface of the filter with silica gel particles during the manufacture of the filter. Free silica gel particles within an electronic enclosure may have harmful effects on the operation of the electronic components within the enclosure. Silica gel particles are typically defined as hard particles, and as such, their presence can cause damage to electronic components. For example, if a hard silica particle enters the clearance between a rotating platen of a disk drive and the drive head, a drive crash may result. This can result in loss of data.
Improved filters for electronic enclosures are needed. In particular, a filter for an electronic enclosure that does not contain hard particles is desired.